1. Field of the Invention
The present invention relates to a vehicle door sash that is formed by extrusion molding.
2. Description of Related Art
A vehicle door sash that is formed using an aluminum alloy extruded product with the purpose of reducing the weight of the vehicle door sash, instead of using a conventional rolled product of an iron-based material, has been proposed and been made practically viable (Japanese Unexamined Patent Publication No. 2007-145282).
However, although an extruded vehicle door sash is advantageous with regard to weight reduction, it is a technical challenge to maintain a desired strength while achieving a reduced material-thickness. In particular, in an extruded product, unlike in the case of a rolled product, it is necessary to carry out a subsequent process (vertical-pillar sash bending process) on the linearly extruded material in accordance with the curvature (bulging shape) of the vehicle body in the lateral (vehicle width) direction in the case of a vertical-pillar sash, and it is essential to carry out a subsequent process (upper sash bending) on the linearly extruded material in accordance with the side-surface shape of the sash in the case of an upper sash. Hence, this linearly extruded material requires a predetermined strength so as not to buckle during the above-mentioned subsequent processes.